scholarly journals Influence of Oxygen-Containing Sulfur Flavor Molecules on the Stability of β-Carotene under UVA Irradiation

Molecules ◽  
2019 ◽  
Vol 24 (2) ◽  
pp. 318 ◽  
Author(s):  
Gong-Liang Zhang ◽  
Hong-Yan Wu ◽  
Ying Liang ◽  
Jie Song ◽  
Wei-Qi Gan ◽  
...  
Keyword(s):  
Sulfur Atom ◽  
Critical Role ◽  
Oxidation Products ◽  
First Order ◽  
Uva Irradiation ◽  
First Order Kinetics ◽  
Dynamic Degradation ◽  
The Stability ◽  
Ethanol System ◽  
Β Carotene

The influence of 11 kinds of oxygen-containing sulfur flavor molecules was examined on β-carotene stability under UVA irradiation in ethanol system. Both the effects of sulfides on dynamic degradation of β-carotene and the relation between structure and effect were investigated. The oxidation products of β-carotene accelerated by sulfides under UVA irradiation were also identified. The results indicated that the disulfides had more obvious accelerative effects on the photodegradation of β-carotene than mono sulfides. The degradation of β-carotene after methyl (2-methyl-3-furyl) disulfide (MMFDS), methyl furfuryl disulfide (MFDS) and bis(2-methyl-3-furyl) disulfide (BMFDS) exposure followed first-order kinetics. Furan-containing sulfides such as MMFDS and BMFDS showed more pronounced accelerative effects than their corresponding isomers. The oxidation products were identified as 13-cis-β-carotene, 9,13-di-cis-β-carotene and all-trans-5,6-epoxy-β-carotene. These results suggest that both the sulfur atom numbers and the furan group in oxygen-containing sulfides play a critical role in the photooxidation of β-carotene.

scholarly journals Effects of different water activities on the stability of carotenoids in puff-dried yellow peach powder during storage

2021 ◽  
Vol 13 (SP2) ◽  
pp. 1-8
Author(s):  
Gorby Gonzalles ◽  
Ningning Geng ◽  
Shuwei Luo ◽  
Chenchen Zhang ◽  
Caie Wu ◽  
...  
Keyword(s):  
Water Absorption ◽  
Water Activity ◽  
Adsorbed Water ◽  
X Ray Diffraction ◽  
Total Carotenoids ◽  
X Ray ◽  
First Order ◽  
First Order Kinetics ◽  
The Stability ◽  
Β Carotene

The stability of carotenoids in puff-dried yellow peach powder during commercial storage under different water activity conditions was studied. The results showed that when the corresponding water activity was above 0.576, the loss of adsorbed water in yellow peach powder was closely related to the crystallinity of the amorphous sugar matrix. However, the adsorption isotherms confirmed by water absorption behavior, X-ray diffraction (XRD) pat-terns, and scanning electron microscopy did not clearly indicate this loss of adsorbed water. The content changes of individual carotenoids (lutein, zeaxanthin, β-cryptoxanthin, α-carotene, and β-carotene) during storage followed pseudo first-order kinetics, and the degradation of lutein and zeaxanthin occurred quickly over time. The stability of total carotenoids gradually increased when the water activity was less than 0.576, but the carotenoids degraded sharply when the water activity was between 0.753 and 0.843. The loss of carotenoids was related to the water absorption and crystallization of the sugar matrix in the powder.

scholarly journals Bleaching of chlorophylls by UV irradiation in vitro: The effects on chlorophyll organization in acetone and n-hexane

2008 ◽  
Vol 73 (3) ◽  
pp. 271-282 ◽  
Author(s):  
Jelena Zvezdanovic ◽  
Dejan Markovic
Keyword(s):  
Uv Irradiation ◽  
Photosynthetic Pigments ◽  
Energy Input ◽  
First Order ◽  
First Order Kinetics ◽  
Uv Photons ◽  
The Stability ◽  
Major Factors

The stability of chlorophylls toward UV irradiation was studied by Vis spectrophotometry in extracts containing mixtures of photosynthetic pigments in acetone and n-hexane. The chlorophylls underwent destruction (bleaching) obeying first-order kinetics. The bleaching was governed by three major factors: the energy input of the UV photons, the concentration of the chlorophylls and the polarity of the solvent, implying different molecular organizations of the chlorophylls in the two solvents.

Use of purified lyophilized human lactate dehydrogenase isoenzyme 5 in a study of measuring lactate dehydrogenase activity.

1989 ◽  
Vol 35 (8) ◽  
pp. 1774-1776 ◽  
Author(s):  
D A Smith ◽  
G C Moses ◽  
A R Henderson
Keyword(s):  
Lactate Dehydrogenase ◽  
Half Life ◽  
Specific Activity ◽  
Lactate Dehydrogenase Activity ◽  
Bovine Albumin ◽  
First Order ◽  
First Order Kinetics ◽  
The Stability ◽  
Lactate Dehydrogenase Isoenzymes ◽  
Excellent Stability

Abstract We examined the stability of human lactate dehydrogenase (EC 1.1.1.27) isoenzyme 5--purified to a specific activity of about 400 kU/g--when lyophilized in a buffered, stabilized matrix of bovine albumin. This isoenzyme was prepared with a final activity of about 500 U/L and stored at -20, 4, 20, 37, and 56 degrees C for as long as six months. This isoenzyme decayed with approximate first-order kinetics, with an estimated half-life at -20 degrees C of about 475 years. Stability of reconstituted samples stored at 20 or 4 degrees C was poor, suggesting that the reconstituted material should be used without delay; material stored at -20 degrees C showed excellent stability for 15 days. We propose that such preparations might be further investigated as standards for use in electrophoresis of lactate dehydrogenase isoenzymes.

Reaction of Glutathione with Conjugated Carbonyls

1975 ◽  
Vol 30 (7-8) ◽  
pp. 466-473 ◽  
Author(s):  
Hermann Esterbauer ◽  
Helmward Zöllner ◽  
Norbert Scholz
Keyword(s):  
Catalytic Effect ◽  
Biological Activities ◽  
Equilibrium Constants ◽  
Reverse Reaction ◽  
Mesityl Oxide ◽  
Forward Reaction ◽  
First Order ◽  
First Order Kinetics ◽  
Proton Donors ◽  
The Stability

Abstract 1. GSH reacts with conjugated carbonyls according to the equation: G SH+R-CH=CH-COR⇆R-CH(SG)-CH2-COR. The forward reaction follows second order, the reverse reaction first order kinetics. It is assumed that this reaction reflects best the ability of conjugated carbonyls to inactivate SH groups in biological systems. 2. The rate of forward reaction increases with pH approx. parallel with αSH. Besides OH- ions also proton donors (e. g. buffers) increase the rate. The catalytic effect of pH and buffer is inter­ preted in view of the reaction mechanism. 3. The equilibrium constants as well as the rate constants for forward (k1) and reverse reaction show an extreme variation depending on the carbonyl structure. Acrolein and methyl vinyl ketone (kt = 120 and 32 mol-1 sec-1 , resp.) react more rapidly than any other carbonyl to give very stable adducts (half-lives for reverse reaction 4.6 and 60.7 days, resp.). Somewhat less reactive are 4-hydroxy-2-alkenals and 4-ketopentenoic acid (k1 between 1 and 3 mol-1 sec-1), but they also form very stable adducts showing half-lives between 3.4 and 19 days. All other carbonyl studied react either very slowly (e. g. citral, ethly crotonate, mesityl oxide, acrylic acid) or form very labile adducts (crotonal, pentenal, hexenal, 3-methyl-butenone). Comparing biological activities of con­ jugated carbonyls their reactivity towards HS (k1) and the stability of the adducts must be considered.

scholarly journals Interactions of natural antioxidants with red grape pomace anthocyanins in a liquid model matrix: Stability and copigmentation effects

2011 ◽  
Vol 17 (1) ◽  
pp. 59-66 ◽  
Author(s):  
Badherdine Sidani ◽  
Dimitris Makris
Keyword(s):  
Ascorbic Acid ◽  
Natural Antioxidants ◽  
Grape Pomace ◽  
First Order ◽  
First Order Kinetics ◽  
Model Matrix ◽  
Liquid Model ◽  
Matrix Stability ◽  
The Stability ◽  
Red Grape

The purpose of this study was an examination on the stability and colour enhancement of red grape pomace anthocyanins in a juice model matrix, and the effect of the addition of natural antioxidants. The approach was based on a juice-like liquid medium (10.1?Brix, pH 3.48), which was used as the model matrix to test the effect of the addition of natural antioxidants (L-cysteine, ascorbic acid, catechin and quercetin) on the degradability of anthocyanin pigments, extracted from grape pomace. It was found that treatment of the model solutions at 80?C induced anthocyanin decomposition, which obeyed first order kinetics. Addition of increasing amounts of antioxidants, including L-cysteine, ascorbic acid, catechin and quercetin, did not provoke a proportional impact, either positive or negative, with regard to anthocyanin stability. The best stabilising effect was seen after addition of ascorbic acid and catechin at concentrations of 4 and 2 mg L-1, respectively (P < 0.001). Quercetin, however, was demonstrated a very efficient co-pigment, inducing an increase in A520 by 63%, at pH 5.6 and a copigment-to-pigment ratio of 10.

Stability of dicyclohexylcarbodiimide in an aqueous medium. The effect of mitochondrial phospholipids

1983 ◽  
Vol 48 (2) ◽  
pp. 662-667 ◽  
Author(s):  
Jan Kopecký ◽  
Stanislav Pavelka ◽  
Jiří Dědina ◽  
Věra Siglerová ◽  
Karel Vereš
Keyword(s):  
Test Tube ◽  
Chemical Modifier ◽  
Specific Chemical ◽  
First Order ◽  
First Order Kinetics ◽  
Membrane Bound ◽  
Pseudo First Order ◽  
Ph Dependent ◽  
The Stability ◽  
Membrane Bound Enzymes

The stability of N,N'-dicyclohexylcarbodiimide (DCCD) was analyzed with respect to the use of DCCD as a specific chemical modifier of membrane-bound enzymes. The disappearance of DCCD from the sucrose-Tris medium obeyes the pseudo-first-order kinetics the rate constant (kd) of which is pH-dependent (kd = 12.0 . 10-3 min-1 at pH 6.0, and kd = 1.6 . 10-3 min-1 at pH 9.0, respectively). However, the rate of the total [14C]DCCD binding to mitochondrial membrane proteins is not markedly influenced by the change of pH (6.0-9.0). The rate of DCCD disappearance is enhanced in the presence of mitochondrial phospholipids. It is concluded that the rapid equilibration of DCCD between the phospholipid and water phase, the reactivity of DCCD with phospholipids, H+-stimulated hydration of DCCD to dicyclohexylurea and the sorption of DCCD to the test tube must be considered when studying the interaction of DCCD with membrane-bound enzymes.

scholarly journals Evaluation of degradation kinetics for abamectin in formulations using a stability indicating method

2013 ◽  
Vol 63 (1) ◽  
pp. 59-69 ◽  
Author(s):  
Atul Awasthi ◽  
Majid Razzak ◽  
Raida Al-Kassas ◽  
Joanne Harvey ◽  
Sanjay Garg
Keyword(s):  
Degradation Kinetics ◽  
Hplc Method ◽  
Degradation Behavior ◽  
Ph Change ◽  
Stability Indicating ◽  
First Order ◽  
Stability Indicating Method ◽  
First Order Kinetics ◽  
Maximum Stability ◽  
The Stability

The aim of this study was to evaluate stability characteristics and kinetics behavior of abamectin (ABM) as a 1 % (m/V) topical veterinary solution. During the study, samples stressed at 55 and 70 °C were regularly analyzed for several parameters over 8 weeks on a chromatographic (HPLC) system, using a Prodigy C18, 250 x 4.6 mm, 5-μm, column eluting with 15 : 34 : 51 (V/V/V) water/methanol/ acetonitrile as mobile phase. The HPLC method was validated for precision, accuracy, linearity and specificity, and was found to be stability indicating. The results showed that degradation of ABM followed first-order kinetics and data on loss in kobs (s-1) and half life (t1/2, days) demonstrated ABM showing the maximum stability in glycerol formal. The degradation behavior of ABM varies from solvent to solvent. The effect of added alkali on pH change and loss of ABM was studied and found to be unique for all solvents and very distinct from typical hydrolysis degradation. The present study may serve as a platform to design and develop topical non-aqueous solutions of ABM for veterinary use given no such comprehensive efforts have been published to date on the stability profile of ABM in non-aqueous solvents.

Use of purified lyophilized human lactate dehydrogenase isoenzymes in a study of the measurement of lactate dehydrogenase activity.

1986 ◽  
Vol 32 (5) ◽  
pp. 758-762 ◽  
Author(s):  
D A Smith ◽  
G C Moses ◽  
A R Henderson
Keyword(s):  
Lactate Dehydrogenase ◽  
Zero Order ◽  
Lactate Dehydrogenase Activity ◽  
First Order ◽  
First Order Kinetics ◽  
Activity Concentrations ◽  
Zero Order Kinetics ◽  
Specific Activities ◽  
The Stability ◽  
Lactate Dehydrogenase Isoenzymes

Abstract We examined the stability of human lactate dehydrogenase (EC 1.1.1.27; LD) isoenzymes 1, 2, and 3--purified to specific activities of about 200 kU/g--when lyophilized in a buffered stabilized matrix of bovine albumin. Each isoenzyme was prepared at two activity concentrations and stored at -20, 4, 20, 37, and 56 degrees C for as long as six months. LD-1 activity decayed with zero-order kinetics, LD-2 and LD-3 with first-order kinetics. The extrapolated half-lives of these preparations at -20 degrees C varied between 80 and 530 years. Stability of reconstituted samples stored at 4 degrees C was excellent for LD-1 but poor for LD-2 and LD-3. We suggest that preparations of human LD-1 be further investigated as a possible reference material.

scholarly journals Extraction of bioactive compounds and free radical scavenging activity of purple basil (Ocimum basilicum L.) leaf extracts as affected by temperature and time

2016 ◽  
Vol 88 (2) ◽  
pp. 1055-1068 ◽  
Author(s):  
ALESSANDRA C. PEDRO ◽  
FERNANDA MOREIRA ◽  
DANIEL GRANATO ◽  
NEIVA D. ROSSO
Keyword(s):  
Bioactive Compounds ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Ocimum Basilicum ◽  
Anthocyanin Content ◽  
Leaf Extracts ◽  
First Order ◽  
First Order Kinetics ◽  
Potential Source ◽  
The Stability

In the current study, response surface methodology (RSM) was used to assess the effects of extraction time and temperature on the content of bioactive compounds and antioxidant activity of purple basil leaf (Ocimum basilicum L.) extracts. The stability of anthocyanins in relation to temperature, light and copigmentation was also studied. The highest anthocyanin content was 67.40 mg/100 g extracted at 30 °C and 60 min. The degradation of anthocyanins with varying temperatures and in the presence of light followed a first-order kinetics and the activation energy was 44.95 kJ/mol. All the extracts exposed to light showed similar half-lives. The extracts protected from light, in the presence of copigments, showed an increase in half-life from 152.67 h for the control to 856.49 and 923.17 h for extract in the presence of gallic acid and phytic acid, respectively. These results clearly indicate that purple basil is a potential source of stable bioactive compounds.

scholarly journals Aminoacetone synthase from goat liver. Involvement of arginine residue at the active site and on the stability of the enzyme

1991 ◽  
Vol 275 (3) ◽  
pp. 575-579 ◽  
Author(s):  
S Ray ◽  
D Sarkar ◽  
M Ray
Keyword(s):  
Active Site ◽  
Arginine Residue ◽  
Enzyme Molecule ◽  
Binding Region ◽  
Acetyl Coa ◽  
Partial Protection ◽  
First Order ◽  
Rate Dependent ◽  
First Order Kinetics ◽  
The Stability

The arginine-specific reagents phenylglyoxal and butane-2,3-dione inactivated goat liver aminoacetone synthase with pseudo-first-order kinetics, with the rate dependent on modifier concentration. Phenylglyoxal and butane-2,3-dione appeared to react with one arginine residue per enzyme molecule. The inactivated enzyme could be re-activated by Tris, suggesting additional evidence of modification of the arginine residue. Acetyl-CoA, one of the substrates, completely protected the enzyme from inactivation. Glycine gave partial protection. Protection by substrates against inactivation by phenylglyoxal and butane-2,3-dione suggested the presence of an essential arginine residue at the substrate-binding region. Experiments with [7-14C]phenylglyoxal in the presence of acetyl-CoA showed that only the arginine residue at the active site could be modified by phenylglyoxal. The stability of the enzyme is dependent on the presence of both EDTA and Mg2+.

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